Process for making 4-butyrolactone

ABSTRACT

4-Butyrolactone can be made by reacting an acetate of butanediol with methanol in the vapor phase in the presence of a catalyst mixture comprising magnesia and a copper dehydrogenating agent.

Smith Dec. 2, 1975 PROCESS FOR MAKING 4-BUTYROLACTONE [75] Inventor: William E. Smith, Schenectady,

[73] Assignee: General Electric Company,

Schenectady, NY.

[22] Filed: Apr. 29, 1974 [21] Appl. No.: 464,802

52 us. Cl. 260/343.6 [51] Int. C1. C07D 307/32 [58] Field of Search 260/3436 [56] References Cited UNITED STATES PATENTS 3,317,563 5/1967 Horlenko et a1 260/3436 FOREIGN PATENTS OR APPLICATIONS 4/1969 Germany 260/3436 1,076,660 3/1960 Germany 260/343.6

Primary Examiner-Anton H. Sutto Assistant Examiner-Jane S. Myers Attorney, Agent, or Firm-Joseph T. Cohen; Jerome C. Squillaro [57] ABSTRACT 4-Butyro1actone can be made by reacting an acetate of butanediol with methanol in the vapor phase in the presence of a catalyst mixture comprising magnesia and a copper dehydrogenating agent.

7 Claims, No Drawings cause tetrahydrofuran to form rather than 4-butyrolac- PROCESS FOR MAKING 4-BUTYROLACTONE tone. In addition, the acid tends to destroy the catalyst mixture, namely, the magnesia and copper dehydro- This invention is concerned with a process for makgenation catalyst. In my method, the methyl acetate ing 4-butyrolactone. More particularly, the invention 5 that forms is neutral and'is inert to the catalyst or to any relates to a process for making 4-butyrolactone which co-product. In addition, the use of the methanol serves comprises reacting at elevated temperatures an acetate as a moderating agent for the reaction and at the same of butanediol with methanol in the vapor phase in the time, seems to have an activating influence on the catapresence of a catalyst mixture comprising magnesia lyst mixture.

and a copper dehydrogenating agent. The process whereby the monoacetate or the diace- 4-Butyrolactone (also known as v-butyrolactone) is a tate of the butanediol can be reacted with the methanol chemical compound which has wide utility as a solvent in the presence of the mixed catalyst system is best ilfor various reactions, as a solvent for high polymers, lustrated by the following two equations using copper and as a chemical and synthetic intermediate used to chromite as an example of a copper dehydrogenation make nylon polymer which, as is well known, has utility catalyst:

TI) 0 C I Magnesia .HO-(CH2)4OC-CH3+CH3OH CH2 0 +CH3OCCH3+2H2 CuCrO CH CH (I? O C ll ll Magnesia CH --CO-(CH OCCH +2CH OH H; O +2CH3OCCH3+2H2 cucro,

CH2-CH2 in the apparel and insulation arts. The catalysts that may be employed in the invention I have now discovered a relatively simple method for are magnesiain its various forms including magnesium making the lactone from either the monoacetate of buoxide, and magnesium oxide mixed with m'agnesium tanediol or the diacetate of butanediol by reacting the hydroxide. Magnesia compositions of the type delatter with methanol in the vapor phase at elevated scribed in US. Pat. No. 3,748,282 are particularly actemperatures employing a mixture of catalysts compristive in promoting the conversion of the butanediol aceing magnesia and a copper dehydrogenating agent (for tate to the 4-butyrolactone. These catalysts are combrevity hereinafter designated as copper agent). I posed of magnesium oxide, magnesium hydroxide, and have found that in addition to being able to start with manganese oxide promoter. This patent is incorporated butanediol monoor diacetate, I can also start with a herein by reference. I I

mixture of diol derivatives obtained by subjecting allyl 40 The copper dehydrogenating agent, which term is inacetate to the oxo process, namely, 4-aeetoxybutanol, tended to include copper itself, can be any copper com- 3-acetoxy-2-methylpropanol, 2-acetoxybutanol, and pound which can be activated under the influence of their respective diol and diacetate disproportionation hydrogen and is capable of removing hydrogen from products, and still obtain good yields of the 4- organic compounds. The copper salts capable of acbutyrolactone. Such reactions are more particularly complishing this are numerous and well-known in the disclosed and claimed in my copending application Ser. art. Examples of such copper catalysts which may be No. 365,228, filed May 30, 1973, and assigned to the used are, for instance, copper chromite, cupric nitrate, same assignee as the present invention. By reference, cuprous nitrate, copper sulfate, cuprous chloride, cu-

this application is made part of the disclosures of the pric chloride, etc. Generally, the copper dehydrogenatinstant application. This is due to the fact that in my ing agent should be one which is capable of being reprocess, the derivatives of 3-acetoxy-2-methylpropane duced in the presence of hydrogen to the nascent form and Z-acetoxybutanol are converted to low boiling of metallic copper. The copper dehydrogenating agent compounds which are readily removed to permit rapid used should be one which does not adversely affect the and almost complete isolation of 4-butyrolactone. reaction or any of the reactants or by-products.

It is important that the methanol be employed with The amount of magnesia and copper dehydrogenatthe butanediol acetate (which term is intended to ining catalyst employed can be varied widely and is not clude both the monoacetate and the diacetate of bucritical. Since this is a vapor phase reaction, it is genertanediol). It is believed that a dehydrogenation reacally desirable to form a mixture of the magnesia and the tion goes on simultaneously with a reaction between copper dehydrogenating catalyst and position them in the butanediol acetate and the methanol. These reacthe reaction tube. If desired, employing suitable means, tions are believed to be interrelated and dependent the magnesia or the copper dehydrogenating catalyst upon each other. Thus, the hydrogenation reaction may be deposited on inert carriers such as finely diserves to drive the overall process to completion /ith vided carbon, finely divided graphite, etc. Generally, good yields of the 4-butyrolactone. In addition, the use on a weight basis, one can employ from about 0.5 to 5 of methanol, rather than the use of water with the buparts or more of the copper dehydrogenating agent per tanediol acetate, is essential in order to avoid producpart of the magnesia catalyst. Little difficulty should be ing any acidic by or co-products. If a hydrolysis encountered in determining the amounts of the magnemethod were used, the acetic acid produced would sia andcopper dehydrogenating agent employed in the 3 reaction zone over which the mixture of the methanol and the butanediol acetate is passed.

The temperatures at which the process can be carried out can vary widely. Generally, elevated temperatures are required since it is a vapor phase reaction. I have found that temperatures ranging from about 150 to 300C. are generally adequate, and preferably the reac tion is carried out at a temperature of from about l75 to 250C. The maximum temperature should be below the temperature at which destruction or decomposition of the reactants or their products occurs.

In addition to atmospheric pressure, as is normally employed, it will be apparent to those skilled in the art that superatmospheric or even subatmospheric pressures may be employed where conditions warrant.

The means for carrying out the reaction to form the butyrolactone may be varied widely. Since this is a vapor phase reaction, it is essential that one employ a hot tube reactor adequately supplied with heating means. Generally, the catalyst mixture is packed in the tube, using a catalyst support if desired. Thereafter, applying heat and using a slow hydrogen stream through the reaction tube (which is used for increasing the activity of the catalyst mixture), the mixture of the butanediol acetate and the methanol are introduced and allowed to course through the tube over the heated bed of the catalyst mixture for a sufficient time (residence times on the order of about 3 to seconds are usually satisfactory). The effluent materials are then removed from the exit end of the tube and condensed. The butyrolactone obtained can be isolated in essentially pure form. The unreacted materials can be recycled to the reaction zone on a continuous basis. Removal of the methyl acetate at the top of the reactor aids in driving the reaction in the direction of butyrolactone formation.

In order that those skilled in the art may better understand how the present invention may be practiced, the following examples are given by way of illustration and not by way of limitation.

The apparatus employed in the following examples comprised a vertical hot tube reactor (16 mm ID X 70 cm effective length) constructed from heavy wall glass, with 24/40 male and female joints. Vigreaux points were indented just above the male joint to support catalyst pellets. Thermocouple leads were fastened into three other Vigreaux indentations at points along the length. Three 4 ft. X 1 in. glass insulating heating tapes were wound around the tube, covered with glass wool and glass tape, and connected to separate variable transformers. The tube exit was connected by a gooseneck (also heated) to a condenser and collection vessel. A three-necked flask served as the evaporator with the reactants added from an addition funnel in a side neck.

EXAMPLE 1 The tube described above was charged with a mixed catalyst composed of 132 grams of copper chromite (Harshaw Cu-0203 T, Vs pellets) and 58 grams of magnesia catalyst in the form of 3/l6" pellets containing 54%- magnesium oxide, 42% magnesium hydroxide, and 4% manganese oxide. The system was then heated at l90-200C. while passing a slow hydrogen stream through the tube. Simultaneously, a mixture of 50 grams butanediol diacetate and 150 grams methanol was introduced over a two-hour period so that there was a residence time of the mixture of organic materials in the tube of about 3 to 10 seconds. A direct quantitative glpc (gas-liquid partition chromatography) analysis (diphenylmethane internal standard) of the condensed effluent showed the presence of 5.8 grams of l,4-butanediol diacetate (12% unconverted), 2.4 grams of 4-acetoxybutanol (6% yield, 6% unconverted). 16 grams of 4butyrolactone (78% yield based on 82% conversion), and 27.7 grams of methyl acetate (77% yield based on 85% conversion of available acetate).

EXAMPLE 2 When crude monoacetate of butanediol comprising the product obtained by subjecting allyl acetate to the oxo process (containing in addition small amounts of 3-acetoxy-2-methyl propane, Z-acetoxybutanol, their corresponding diacetates, and l,4-butanediol diacetate) was reacted with methanol in the same way as was done in Example 1, the conversion and yield of 4- butyrolactone was qualitatively and quantitatively almost the same as when the butanediol diacetate was employed.

It should be noted that when methanol was reacted with the butanediol diacetate in the presence of the copper chromite alone, a relatively low conversion (about 20%) of the butanediol diacetate was obtained even at the more elevated temperature of 250C. This illustrates the importance of having the combined catalyst mixture of the magnesia and the copper dehydrogenation agent.

EXAMPLE 3 Employing the same tube reactor and conditions as described in Example 1, the tube was charged with 156 grams of catalyst prepared by impregnating pellets of magnesium oxide with 8%, by weight, thereof of cupric nitrate. The catalyst bed mixture was heated at about 180 to 200C. under a hydrogen stream and while the hydrogen was continually passed through, a mixture of 50 grams of l,4-butanediol diacetate and grams of methanol was introduced into the tube over 2 hours, so that the mixture of the reactant as it passed through the tube had a residence time of about 3 to 10 seconds. Analysis of the effluent gas by glpc showed that as a result of a single pass, 20% of the starting material was converted to the 4-butyrolactone. Another 30% of the diacetate had been converted to the butanediol monoacetate, while the balance of the effluent was methanol and unchanged butanediol diacetate. The corresponding amount of methyl acetate was also found. ,It will be apparent that a recycle of the unreacted materials and the butanediol acetate to the reaction zone would additionally convert the reactants to the desired 4-butyrolactone.

It will of course be apparent to those skilled in the art that in addition to the magnesia catalysts employed above, other magnesia type catalysts, many examples of which are given in the above-identified US. Pat. No. 3,748,282 may be employed without departing from the scope of the invention. The conditions of reaction and the manner of introduction of the reactants can also be varied within wide limits.

What I claim as new and desire to secure by Letters Patent:

1. The process for making 4-butyrolactone which comprises reacting, in the presence of hydrogen at a temperature in excess of 150C., an acetate of butanediol with methanol in the vapor phase in the presence above 150C. in the presence of hydrogen, a mixture comprising a butanediol acetate and methanol in the presence of a catalytic mixture consisting essentially of (l) a mixture of magnesium oxide and magnesium hydroxide, and (2) copper chromite.

6. The process as in claim 1 wherein the copper dehydrogenating agent is copper nitrate.

7. The process as in claim 1 wherein the copper dehy- 10 drogenating agent is copper chromite. 

1. THE PROCESS FOR MAKING 4-BUTYROLACETONE WHICH COMPRISES REACTING IN THE PRESENCE OF HYDROGEN AT A TEMPERATURE IN EXCESS OF 150*C., AN ACETATE OF BUTANEDIOL WITH METHANOL IN THE VAPOR PHASE IN THE PRESENCE OF A CATALYST MIXTURE CONSISTING ESSENTIALLY OF MAGNESIA AND A COPPER DEHYDROGENATING CATALYST.
 2. The process as in claim 1 wherein the magnesia catalyst is a mixture of magnesium oxide, magnesium hydroxide and manganese oxide.
 3. The process as in claim 1 wherein the butanediol ester is the monoacetate of butanediol.
 4. The process as in claim 1 wherein the butanediol ester is the diacetate of butanediol.
 5. A process for preparing 4-butyrolactone which comprises heating in the vapor phase at a temperature above 150*C. in the presence of hydrogen, a mixture comprising a butanediol acetate and methanol in the presence of a catalytic mixture consisting essentially of (1) a mixture of magnesium oxide and magnesium hydroxide, and (2) copper chromite.
 6. The process as in claim 1 wherein the copper dehydrogenating agent is copper nitrate.
 7. The process as in claim 1 wherein the copper dehydrogenating agent is copper chromite. 